个人简介

Education Ph.D Texas A&M University 1994 B.S. University of Texas, Tyler 1989 Welch Postdoctoral Fellow Texas A&M University, College Station 1994 Postdoctoral Fellow National High Magnetic Field Laboratory, ICR Program, FL 1994-1997 Experience Senior Scientist, Chem/Bio Defense Illinois Institute of Technology Research Institute, Chicago, IL 1997 Assistant Professor of Chemistry University of Maine, Orono, ME 1997-2003 Associate Professor of Chemistry & Cooperating Professor within the Graduate School of Biomedical Sciences (GSBS) University of Maine, Orono, ME 2003-2010 Professor, Department of Chemistry University of Maine, Orono, ME 2010 - 2011 Professor of Chemistry & and Biochemistry Baylor University, Waco, TX 2011 - present

研究领域

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Bioanalytical, Environmental, Instrumental, and X-omics Research

Analyses of complex biological and environmental sample mixtures require state-of-the-art instruments that can resolve different components of a mixture, provide individual molecular identities, yield relative abundance or concentration information, and unravel potential molecular interactions among the various constituents of a complex sample at a high level of confidence. Our studies are focused on biomedical and environmental research and improving performance characteristics of modern mass spectrometers to address the demanding analytical requirements for comprehensive characterization of complex mixtures in the emerging areas of "x-omics". Here, we use "x-omics" to refer to inclusive study of complex systems such as the components of a living organism (e.g., genomics, metabolomics, proteomics, etc) and/or a non-living system (e.g., petroleumics). Ideally, for complete characterization of a complex ensemble, three general questions regarding the (i) types, (ii) concentrations, and (iii) nature of the interactions of all individual components of a mixture under the investigation must be addressed (often, as a function of time). Our research addresses all of the above mentioned three areas and includes activities from instrument development endeavors, experimental approaches, and theoretical calculations. Specifically, our research group's interests include structural analysis of complex molecules by collision-induced dissociation (CID), electron capture dissociation (ECD), and photodissociation in Fourier Transform Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry and development of high performance analytical devices and multidimensional methods. We are utilizing various "hard" and "soft" ionization techniques such as electron impact ionization (EI), chemical ionization (CI), self chemical ionization (SCI), and electrospary ionization (ESI) for sample fingerprinting and understanding chemical interactions in complex mixtures at the molecular level. Several of our current research projects focus on reducing mass spectral detection limits (e.g., the use of cryofocusing for GC/MS analysis of volatile compounds and external ion accumulation in ESI experiments) for the analysis of environmental toxins and biomolecules in various areas of "x-omics" addressing emerging needs both in instrumental development and introduction of multidimensional techniques, that include ion mobility spectrometry (IMS), experimental measurement of thermochemical properties such proton affinities (PAs) and gas phase basicites (GB) and their theoretical calculations, for comprehensive characterization of complex samples mixtures. Also a major portion of our current research focuses on biomarker identification for early and non-invasive detection of human diseases such as cancer. In this endeavor, we attempt to address contemporary challenges related to the fundamental chemistry, bioinformatics, and applied aspects of complex data analysis. For instance, a major portion of our efforts is focused on utilizing gas-phase ion-molecule reaction kinetics such as hydrogen-deuterium exchange (HDX) combined with IMS conformational analyses to improve structural characterization of proteins and their fragments in "bottom-up" and "top-down" proteomics. In these two proteomic approaches, either digested (in bottom-up) or intact (in top-down) proteins are fragmented using activational {e.g., collision-induced dissociation (CID), infrared multiphoton dissociation (IRMPD)} and/or non-activational {e.g., electron capture dissociation (ECD) and electron transfer dissociation (ETD)} dissociation techniques. The product fragment ions are searched against databases or theoretical MS/MS spectra using computer algorithms for protein/peptide sequence identification. Reliability of protein/peptide identification using computer algorithms depends, in part, on the extent and types of protein/peptide dissociation products. Computer-based protein/peptide identification is usually performed without (or with little) insight into the rules that govern peptide dissociation and fragmentation. However, for accurate bioinformatics-based MSn sequencing of proteins/peptides, basic knowledge of the chemistry and mechanisms of gas-phase peptide fragmentation are crucial. For instance, unaccounted "ion rearrangements" can impede gas-phase protein sequencing and our systematically designed tandem MS research in this area addresses the issues related to amino acid "sequence scrambling" in tructural and biological mass spectrometry.